1. Field of the Invention
The present general inventive concept relates to an ink composition including a cyclic silazane-based compound, a colorant, and a solvent. More particularly, the invention relates to an ink composition containing a cyclic silazane-based compound to prevent the formation of ink foam or bubbles in a cartridge when an inkjet printer is operated. The cyclic silazane-based compound induces the rapid elimination of foam or bubbles when produced. The ink composition exhibits a stable initial ink ejection behavior owing to good ink flowability and good long-term storage stability.
2. Description of the Related Art
Recently, with an increase in need/demand for coloration of hard copies in the field of image processing, etc., various methods of producing color hard copies have been developed. Examples of these methods include dye-sublimation recording, thermal wax transfer recording, inkjet recording, electrophotographic recording, and thermally processed silver recording.
In inkjet printing, ink droplets are ejected from nozzles of a recording head of an inkjet printer onto a recording medium such as a paper. The ejected droplets form points called “dots” to create characters and images. The advantages of inkjet printing over other printing methods are its low cost, high quality, and ability to easily produce color images.
Thus, inkjet printers that are capable of simply printing at homes and offices have been widely been used. Inkjet printers that can provide image quality comparable to silver images have also been developed.
Ink used in inkjet printing is prepared by dissolving or dispersing a water-soluble dye or pigment into a solvent including water and a water-soluble organic solvent. If necessary, an additive such as a surfactant may be added.
In order to accomplish good inkjet recording for a long time, water-based ink for inkjet printing must satisfy the following requirements: characteristics such as viscosity, surface tension, and density should have appropriate values, nozzle clogging in an inkjet recording apparatus, precipitate formation due to heat or the like, and a change in physical property values should not occur, and recorded images should have excellent water-repellency and light fastness.
When a large amount of ink is stored in a large capacity ink reservoir used in an inkjet system for a long time, foam or bubbles may be produced in the ink. Furthermore, when air is dissolved in ink, the ink may produce foam or bubbles. In addition, when an ink circulation system is incorporated in a print cartridge, foam or bubbles may form in the print cartridge. The foam or bubbles must be easily removed from the ink or be prevented from being produced. Thus, it is necessary to enhance the defoaming or antifoaming property of ink.
However, in conventional ink compositions, foam or bubbles are easily produced due to the surfactant used as a component of the ink, and thus, the requirements of an ink composition are not satisfied.
In view of this problem, Japanese Patent No. 3,078,184 discloses addition of a fluorine- or silicon-based polymer to the ink.
However, such a polymer is poorly soluble in the ink, and thus, it is necessary to use a solvent that can disperse or dissolve the polymer. Moreover, such a solvent and polymer have poor miscibility with standard water-soluble additives forming the ink. Thus, layer separation and solidification easily occur in the ink, and when the ink is not used for a long time, the silicon polymer and the ink are rapidly dried, thereby rapidly increasing the viscosity of the ink, resulting in nozzle clogging due to ink hardened at a surface of a nozzle of a printhead.
Recent related technology has not yet provided an ink composition capable of preventing the production of ink foam or bubbles in a cartridge, rapidly eliminating foam or bubbles produced, and exhibiting a stable initial ejection behavior and good long-term storage stability.